Apparatus for the development of photographic copies



A ril 30, 1957 a. SCHWIENBACHER 2,790,363

APPARATUS FOR THE DEVELOPMENT OF PHOTQGRAPHIC COPIES Filed Jan. 26, 1953 INVENTOR G. SCHWIENIBACHER ATTORNEY$ United States Patent i APPARATUS FOR THE DEVELOPMENT OF PHOTOGRAPHIQ CGPIES Georges Schwienbacher, Zurich, Switzerland, assignor to Schneto A.-G., Niederdorf, Switzerland Application January 26, 1953, Serial No. 333,076

1 Claim. (Cl. 95-89) The present invention relates to apparatus for developing photographic copies by known processes. With the devices hitherto known for this purpose, the passing of the photographic papers through the developing bath had to be effected by actuating a manual drive, or by a motor with the interposition of reducing gear. Both kinds of drive, owing to the unavoidable fluctuations in the speeds of rev lotion, give rise to a travel of the photographic papers which is not uniform in respect of time, and therefore to an uneven development of the photographic papers. Moreover, the walls of the paper-guiding passages have hitherto been fixedly connected with one another, so that the silver deposit arising produced by the developing process, and causing streak-formation on the photographic paper, the so-called striation, can only be removed with (ill'iiCUlly. Then again the rollers for pressing the photographic papers have hitherto been of comparatively large diameter, so that on the one hand the wet photographic paper, after the squeezing, has been apt to adhere to one of the two rollers and to wind itself around one of them, instead of issuing freely between the two rollers. On the other hand the contact area of photographic papers with rollers of large diameter is so great that a relatively high application pressure is necessary for a good expulsion of the liquid. The length of the arcuate portions of the paths of the photographic papers moving one over another through the developing bath decreases, in the longitudinal cross section of these arcuate paths, in an inward direction considered from the concave side, so that the ends of the paper, which, upon entry into the developing device in the direction of motion of the papers, are still accurately superposed, have become displaced relatively to one another upon entry into the squeezing rollers, which is undesirable.

Now according to the present invention these disadvantages are obviated by the fact that the admission passages provided at the entry into the developing device, which lead to the arcuate portions of the paths of the photographic papers moving one over another in the defleeting wall, in the longitudinal cross section of these arcuate paths considered from the concave side, are rounded out with such a strongly convex curvature that the reduction, increasing in an inward direction, of the lengths of the arcuate portions of the paths of the photographic papers is compensated for. Moreover the admission passages consist of individual walls which can be dismantled in a simple manner; the squeezing rollers have a diameter which amounts to not more than one-tenth of the roller length.

One form of construction of the invention is illustrated by way of example in the accompanying drawing.

in this drawing, 12 denotes the casing of the apparatus, which is provided with three superposed admission passages, and and 11 are the two squeezing rollers. The three admission passages are formed by walls 4, 5, 6 and Patented Apr. 30, 1957 7; and of these the walls 5, 6 and 7, regarded from the concave side of the deflecting wall 9, are rounded out in an upward direction to a convex curvature. This wall 9, which deflects the photographic papers towards the two squeezing rollers lit and 11, is a direct continuation of the wall The length of the passage formed by the walls a and 7 is greater than that of the passage formed by the walls 5 and 6, and that of the passage formed by the walls 5 6 is in its turn greater than that of the passage lormed by the walls 4 and 5. These three passage lengths are so related that the ends of the three photographic papers, located one above another in the direction of motion upon entry into the developing device, after running through the arcuate portions of their paths on the concave side of the arcuate deflecting wall 9 are not deflected relatively to one another, although between themselves they slip relatively to one another. The form of these upwardly rounded admission passages should be as elongated as possible, in order that as little resistance as possible may be opposed to the travel of the photographic papers.

The walls 4, 5, 6 and 7 of the admission passages are kept at a definite distance from one another by spacing discs 3 and 3, and are secured by two laterally applied screws 1 to a thickening 2 of the casing. By unscrewing these two screws 1 the individual walls of the admission passages can be disengaged in a simple manner and easily freed from deposits of silver and other contaminations.

I claim:

An apparatus for developing photographic copies comprising a tank holding a developing solution, inclined spaced apart guide walls within the tank, said guide walls having inlet and outlet ends and forming between adjacent walls a plurality of downwardly directed superposed passages through which passages the papers are adapted to pass, a deflecting wall initially forming a continuation of the lowermost of the guide Walls and terminating in an upwardly curved inclined portion, a pair of squeezing rolls within the tank located immediately above said upwardly curved inclined portion for pressing the papers, each of said guide walls above said lowermost guide wall being formed with an upwardly bulged portion intermedir ate the ends thereof, with such upwardly bulged portions being of such dimensions as to counterbalance the diilerences that would otherwise exist in the distances traversed by the papers as a result of the upwardly curved inclined portion of said lowermost guide wall, spacing discs interposed between said guide walls adjacent to the inlet and outlet ends of said guide walls to maintain said guide walls in proper spaced relationship, a reinforcement element of relatively thick cross-section within the tank at the inlet end of the tank, and screw means passing through the guide walls adjacent the lateral edges of said guide walls and through at least some of the spacing discs into the reinforcement element.

References Cited in the file of this patent UNITED STATES PATENTS 1,513,284 Sinclair Oct. 28, 1924 2,307,142 Lee Jan. 5, 1943 FOREIGN PATENTS 672,844 Great Britain May 28, 1952 847,846 Germany Aug. 28, 1952 515,587 Belgium Nov. 29, 1952 848,013 Germany Dec. 11, 1953 

